The importance of maintaining the cooking temperature of a utensil at a proper temperature is well known. However, in most cases the cooking temperature is not known because there is not readily available a way of measuring it. In the past, most techniques employed for temperature measurement and display have measured the temperature within the cooking utensil indirectly, such as by a device placed on a handle or lid of the utensil. U.S. Pat. Nos. 2,750,916 and 3,736,861 are representative of this indirect technique of measuring temperature for display on the handle of the utensil, and U.S. Pat. Nos. 1,863,918 and 4,509,868 are representative of this indirect technique of measuring temperature for display on the lid of the utensil.
The problem is that since these indirect techniques do not measure the temperature of the utensil's cooking surface, which would be at a higher temperature than is being indicated, the cook may tend to turn the heating plate or burner up to compensate and inadvertently increase the cooking surface above the optimum temperature required to prepare the food.
Temperature regulating thermostats have been provided for waffle irons, but there temperature is regulated only indirectly by placing the thermostat in close proximity to the cooking surface. In waffle irons there are two opposing surfaces, and the temperature that should be controlled is in the space between them. However, it is acceptable to measure temperature indirectly at a site on one side or the other of the pair of waffle plates as shown for example in U.S. Pat. No. 2,159,068. The cooking temperature for waffles is not as critical as for other foods such as for cooking meat.
For cooking food by direct contact with a utensil's surface, such as a pan or griddle, it is necessary to measure the temperature of the cooking surface directly in order to ensure that the proper cooking temperature is being maintained, not only for the cooked food to have the proper taste, but also for the cooked food to be free of all bacteria.